a)Miscarea este
-uniforma in intervalul [40,70]s
-accelerata in intervalul [0,40]s
-incetinita in intervalul [70, 90]s
b)Calculezi acceleratiile medii
[tex]a_{1}=\frac{\Delta v}{\Delta t}=\frac{30-0}{40-0}=0.75\frac{m}{ s^{2} }[/tex][tex]a_{1}=\frac{\Delta v}{\Delta t}=\frac{0-30}{70-90}=1.5\frac{m}{ s^{2} }[/tex]
Si distanta parcursa va fi
[tex]d= \frac{a_{1}* t^{2} }{2} +v*\Delta t+\frac{a_{2}* t^{2} }{2}[/tex]
[tex]d= \frac{0.75* 1600}{2} +30*(70-40)+\frac{1.5*400 }{2}=600+900+300=1800m[/tex]
[tex]d=1.8km[/tex]
